Stop wrestling with individual cell caps and a funnel. The Flow-Rite BG-U48V-4A Pro-Fill system lets you water all 6 of your 8-volt batteries in one controlled fill -- no overfilling, no acid spills, and no manifold required. Designed specifically for battery banks where cell-to-cell spacing falls outside standard golf-cart or RV pack dimensions.
The Pro-Fill universal kit replaces every existing vent cap on your 6-battery, 8-volt bank with precision automatic shut-off valves. Each valve seats directly into the cell opening and cuts off flow the instant electrolyte reaches the correct level -- the same way a toilet float works, but engineered for lead-acid battery chemistry. Interconnecting tubing links all cells into one circuit, so a single fill point services the entire bank.
The "universal" and "non-standard spacing" designation means Flow-Rite ships this kit with extra tubing length and compatible fittings so installers can bridge gaps between batteries that don't conform to a fixed, OEM-spec layout -- common in custom RV battery bays, converted golf carts, floor-mounted industrial packs, and retrofitted solar storage banks.
Float-style valves stop flow at the correct electrolyte level in every cell -- no guessing, no overfill.
Extra tubing and flexible routing accommodate battery bays where cell-to-cell gaps vary from a stock layout.
Tubing connects directly valve-to-valve. Fewer fittings mean fewer potential leak points and a cleaner install.
Kit includes valves for all cells across a full 6-battery, 8V bank -- typically 18 cells total (3 cells per 8V battery).
Each automatic shut-off valve threads into or presses into an individual battery cell vent opening, replacing the factory vent cap. The valves are daisy-chained together with supplied tubing. A single fill coupling -- typically at the end of the chain or at a convenient access point -- connects to a compatible Flow-Rite hand pump, gravity feed bottle, or pressurized water source.
When you fill, water travels through the tubing into each valve simultaneously. The float mechanism inside each valve rises with the electrolyte and seals the inlet when the proper level is reached. Cells that are already full simply close off immediately; cells that need water fill until they reach set level. The result is a correctly watered bank every time, regardless of how uneven the depletion was across cells.
Installation requires no special tools beyond basic hand tools for routing and securing the tubing. The general process:
The BG-U48V-4A kit includes the valves, tubing, and fill coupler, but does NOT include a pump or water source. Flow-Rite sells compatible hand pumps and gravity bottles separately. The fill coupler on Pro-Fill kits uses Flow-Rite's standard quick-connect interface, which mates with their BF and QF series fill accessories.
This system is designed exclusively for flooded lead-acid batteries that require periodic water addition. Do NOT use with AGM, gel, lithium, or sealed VRLA batteries -- those chemistries require no water and have no serviceable vent ports.
Pair this kit with a Flow-Rite hand pump (such as the BF-00PP or similar Pro-Fill pump) or a gravity-feed bottle for a complete single-operator watering station. A dedicated fill handle keeps hands and clothing away from electrolyte during the fill process.